Absorbent article and composite sheet

ABSTRACT

The present invention provides an absorbent article having a composite sheet with a plurality of gathers on an inner surface facing a wearer&#39;s body, which fits and adheres comfortably to the wearer&#39;s skin. The composite sheet is provided which includes a stretchable non-woven fabric which expands and contracts in at least one direction, a non-stretchable non-woven fabric, a junction which binds intermittently the stretchable non-woven fabric to the non-stretchable non-woven fabric in the stretching direction, and a plurality of gathers which is formed by loosening a unbounded area of the non-stretchable non-woven fabric in a contracted state, and is arranged along a direction intersecting the stretching direction, in which an apex of each gather does not reach the neighboring gather when the gathers lean to one side of the stretchable direction.

This application is a continuation of U.S. Ser. No. 11/945,655, filedNov. 27, 2007, which claims the priority of Japanese Application No.2006-319396, filed Nov. 27, 2006, the contents of all of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an absorbent article with a pluralityof gathers on an inner surface facing the wearer's body when wearing anda composite sheet with a plurality of gathers.

2. Related Art

Conventionally, absorbent articles including, for example, disposablediapers, have been proposed. Disposable diapers are widely used forinfants, children, elderly persons and physically handicapped persons,and have replaced reusable cloth absorbent article. Typical disposablediapers are generally composed of a composite structure including a topsheet, a back sheet and an absorbent body between the top and backsheets. The disposable diapers also include a stretchable compositesheet which gives stretchability to a non-stretchable sheet member forimproved adhesion to a wearer's body and cushioning property. Such astretchable composite sheet is realized, for example, by affixing twokinds of non-stretchable sheet members with an expanded stretchablemember therebetween, which can be filiform, plexiform, strip-shaped,sheet-shaped and the like.

When the stretchable member of the stretchable composite sheetcontracts, sheet members form large folds and can impart cushioningproperties therefrom. However, when a wearer moves with a disposablediaper on, adhesion to a wearer's skin worsens and flexibility andtexture deteriorates.

For the reasons stated above, for example, Japanese Unexamined PatentApplication, Publication No. H05-228177 (hereinafter referred to asPatent Document 1) provides a shorts-type sanitary product using anelastic composite, obtained by attaching a non-woven base fabric to oneor both sides of a contracted sheet-shaped elastic body to form gathersin a non-binding site between binding sites, which is joined to anon-woven base fabric side of a portion of the shorts to be stretchable.

The invention disclosed in Patent Document 1 has a structure referred toas floating gathers, which is realized by joining an elastic composite,obtained by binding an elastic body with a non-woven base fabric, to aportion to be stretchable of a shorts-type sanitary product. In the caseof the shorts-type sanitary product disclosed in Patent Document 1, ifthe height of gathers is raised for improved elastic properties, thegathers are flattened and neighboring gathers overlap each other duringwearing. This can deteriorate touch and comfort, and obstruct theexpansion and contraction. Moreover, this can deteriorate adhesion to awearer's body and result in a worsened ability to follow to a wearer'sbody while wearing.

SUMMARY OF THE INVENTION

The present invention was made in view of the aforementioned situation,and the objective is to provide an absorbent article with a plurality ofgathers on an inner surface facing a wearer's body, which fits andadheres comfortably to the wearer's skin, and a composite sheet with aplurality of gathers which can give cushioning property when used.

In order to solve the above problems, the present inventors haveconducted extensive examination. Consequently, the inventor has foundthat arranging a composite sheet, obtained by joining a stretchablenon-woven fabric, which can expand and contract in at least onedirection, to a non-stretchable non-woven fabric on an inner surfacefacing the wearer's body when wearing, gives a superior fit to thewearer's skin, thereby completing the present invention. Morespecifically, the present invention provides the following.

According to a first aspect of the present invention, an absorbentarticle is provided which includes an absorbent body and a chassishaving at least a front body and a back body, in which the compositesheet constitutes or is arranged on the chassis; the composite sheet hasa-stretchable non-woven fabric which expands and contracts at least inone direction, a non-stretchable non-woven fabric, a junction whichbinds intermittently the stretchable non-woven fabric to thenon-stretchable non-woven fabric in the stretching direction, and aplurality of gathers in a non-bound portion between the junctions,formed of loosened parts of the non-stretchable non-woven fabric whilethe stretchable non-woven fabric is in a contracted state along adirection intersecting the stretching direction, and the gathers arearranged on a skin contacting side during wearing.

In a second aspect of the absorbent article as described in the firstaspect of the present invention, the stretching direction includes awaist expanding direction of the absorbent article, and each of thegathers is arranged along the direction substantially orthogonal to thewaist expanding direction.

In a third aspect of the absorbent article as described in the first orsecond aspect of the present invention, each of the gathers is arrangedin an area including a position facing the buttocks of wearer when worn.

In a fourth aspect of the absorbent article as described in any one ofthe first to third aspects of the present invention, the composite sheetis arranged at a predetermined distance away, in the width direction,from a centerline equally dividing the back body, and at each of a pairof areas that are symmetrical to the centerline.

In a fifth aspect of the absorbent article as described in any one ofthe first to fourth aspects of the present invention, a first gather anda second gather, which is adjacent thereto in the stretching directionof the gathers, are formed not to overlap each other in a case where thefirst and the second gathers lean.

In a sixth aspect of the absorbent article as described in the fifthaspect of the present invention, the absorbent article satisfies thefollowing Formula 1 in which A is a width in the stretching direction ofa junction where the non-stretching non-woven fabric is bound to thestretching non-woven fabric, B is a length in the stretching directionof the region of the non-stretchable non-woven fabric not bound to thestretchable non-woven fabric, and C is a distance in the stretchingdirection between each of the junctions.B<C+2A  Formula 1

In a seventh aspect of the absorbent article as described in any one ofthe first to sixth aspects of the present invention, a first gather anda second gather, which is adjacent thereto in the stretching directionof the gathers, are formed not to overlap each other in a case the firstand the second gathers lean facing each other.

In an eighth aspect of the absorbent article as described in the seventhaspect of the present invention, the absorbent article satisfies thefollowing Formula 2 in which A is a width in the stretching direction ofa junction where the non-stretching non-woven fabric is bound to thestretching non-woven fabric, B is a length in the stretching directionof the region of the non-stretchable non-woven fabric not bound to thestretchable non-woven fabric, and C is a distance in the stretchingdirection between each of the junctions.B<A+C  Formula 2

According to a ninth aspect of the present invention, a composite sheetis provided which includes: a stretchable non-woven fabric which expandsand contracts in at least one direction; a non-stretchable non-wovenfabric; a junction which binds intermittently the stretchable non-wovenfabric to the non-stretchable non-woven fabric in the stretchingdirection; and a plurality of gathers which is formed by loosening aunbounded area of the non-stretchable non-woven fabric in a contractedstate, and is arranged along a direction intersecting the stretchingdirection, in which an apex of each gather does not reach theneighboring gather when the gathers lean to one side of the stretchabledirection.

The present invention can provide an absorbent article and a compositesheet that fit and adhere comfortably to a wearer's skin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a main body of the disposable diaper in aflattened state;

FIG. 2 is a front view of a main body of the disposable diaper;

FIG. 3 is a top view of a main body of the disposable diaper with acomposite sheet arranged in the back body in the flattened state;

FIG. 4 is a top view of a main body of the disposable diaper with acomposite sheet arranged in the vicinity of the buttocks in theflattened state;

FIG. 5 is a perspective view of the composite sheet;

FIG. 6 is a perspective view of the composite sheet;

FIG. 7 is a diagram showing an example of manufacturing the stretchablenon-woven fabric;

FIG. 8 is a chart showing the degree of comfort to the wearer's body ofthe main body of the disposable diaper; and

FIG. 9 is a chart showing the degree of softness to the touch of theabsorbent body of the disposable diaper.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are described in detailbelow. It should be noted that the present invention is not limitedthereto, and can be changed and implemented as necessary to implement inthe scope of the objective of the present invention. It should also benoted that, although redundant descriptions are omitted, the presentinvention is not limited thereby.

In the preferred embodiments, it is assumed that the side of thedisposable diaper facing a wearer's body is a skin contacting side, andthe side opposite the skin contacting side is a skin non-contactingside.

First Embodiment of an Absorbent Article

FIG. 1 is a top view of a disposable diaper in the flattened stateaccording to a first embodiment of the present invention. FIG. 2 is afront view of a main body of the disposable diaper. The disposablediaper 1 includes a chassis 14, a liquid permeable top sheet 11, aliquid impermeable back sheet 12 and a liquid retentive absorbent body13. The chassis 14 forms the outline of the disposable diaper 1, and iscomposed of a front body 141 and a back body 142 that are shaped into ashorts shape during wearing. The liquid permeable top sheet 11 isdisposed on the skin-contacting side of the chassis 14, and has asubstantially elongated shape forming a top layer. The liquidimpermeable back sheet 12 is disposed on the skin non-contacting side ofthe chassis 14 as one side of the top sheet 11, and has a substantiallyelongated shape forming a back layer. The liquid retentive absorbentbody 13 is disposed between the top sheet 11 and the chassis 14, and hasa substantially elongated shape forming an absorbent layer. It should benoted that the term substantially elongated shape includes a shape inwhich a portion of both sides in the longitudinal direction LD istapered to the center in the longitudinal direction LD or bulged in thedirection opposite the center. Specifically, the absorbent body 13includes an absorbent body 13 that is different in length in the widthdirection WD in a portion in the longitudinal direction LD.

The absorbent body 13 may be arranged in the state of being covered withtissues (not shown) or a hydrophilic non-woven fabric (not shown). Whencovered with a hydrophilic non-woven fabric, the absorbent body 13 maybe configured without application of the liquid permeable top sheet 11or with only a partial application thereof. This allows for a reductionin manufacturing cost, for example.

The chassis 14 includes a front body 141, a back body 142, and a crotch143 arranged therebetween during wearing. The chassis 14 is formed toprovide a shorts shape by joining the front body 141 and the back body142 at predetermined locations of the front body 141 and the back body142. Specifically, the chassis 14 includes a waist opening 16 formedaround a wearer's abdomen and a pair of leg openings 15 formed around awearer's legs during wearing. It should be noted that the predeterminedlocation of the front body 141 and the back body 142 designates bothends of the front body 141 and the back body 142 in the direction(referred hereafter to as width direction WD) orthogonal to the risedirection RD in the worn state except for the leg openings 15. The frontand rear bodies 141 and 142 include, for example, front and rear bodiesdistinguished by the center line parallel to the width direction WD,which bisects the disposable diaper 1 in the longitudinal direction LD.

The front and rear bodies 141 and 142 are composed of, or arranged by, acomposite sheet 17 obtained by laminating (joining) a stretchablenon-woven fabric 172 and a non-stretching non-woven fabric 171. Thecomposite sheet 17 is arranged between a waist opening 16 and a pair ofleg openings 15. In the present embodiment, the composite sheet 17expands and contracts in the width direction WD. A plurality of gathers(or folds) 174 is formed of a non-stretchable nonwoven fabric 171 on oneside (skin contacting side in the present embodiment) of a stretchablenon-woven fabric 172 of a composite sheet 17. The plurality of gathers174 is arranged along a direction intersecting the stretching directionof the composite sheet 17. For example, each of the plurality of gathers174 is arranged along a direction (longitudinal direction LD)substantially orthogonal to the width direction WD. Each of theplurality of gathers 174 is formed in the width direction WD atsubstantially equal intervals.

The disposable diaper body 1 is formed to provide a shorts shape,including a trunk opening 16 and a pair of leg openings 15, by joiningthe front body 141 and the back body 142 at the junctions 18 as shown inFIGS. 1 and 2.

It should be noted that, although a disposable diaper body 1 isdescribed in the preferred embodiments, the present invention is notlimited thereto. For example, it may be a disposable diaper body 1formed to provide a shorts shape, including a trunk opening 16 and apair of leg openings 15, by joining the front body 141 and the back body142 at the junctions 18. It may also be used in an expansion-typedisposable diaper which can be worn by engaging the front body 141 andthe back body 142 with an engaging member and the like.

Alternatively, an engaging member such as a surface fastener used in theexpansion-type disposable diaper 1 may be disposed at the junction 18 inthe front body 141 and the rear body 142 of a pants-type disposablediaper. This provides a disposable diaper of a pants-type that can beexpanded and re-engaged by easy release and engagement.

Furthermore, in the present invention, a leak preventing wall (notshown), which can be formed by using a leak preventing sheet, may bearranged along both ends in the width direction (WD) of the absorbentbody 13 of the disposable diaper.

Although a liquid impermeable back sheet 12 is arranged on the skinnon-contacting side, without being limited thereto, the back sheet 12may be arranged between the absorbent body 13 and the chassis 14 orbetween sheets when the chassis 14 includes a plurality of sheets.

In this case, the liquid permeable top sheet 11 and the absorbent body13 are adhesively joined to each other with a hot-melt adhesive. Inaddition, the liquid permeable top sheet 11 and absorbent body 13 areadhesively joined to the chassis 14 with the hot-melt adhesive. In asimilar way, the chassis 14 and the liquid impermeable back sheet 12 areadhesively joined to each other with the hot-melt adhesive.

The front body 141 and back body 142 are intermittently joined at thejunction 18 using ultrasonic sealing. As another connecting method atthe junction 18, hot sealing or a hot-melt adhesive may be used to makethe connection.

For the disposable-diaper main body, a plurality of filiform elasticmembers (not shown) are arranged at the circumference of the waistopening 16. The elastic members may be strip-shaped. The elastic membersmay include an elastic sheet that can stretch, such as a stretchablenon-woven fabric (non-woven fabric formed of mixed fibers ofpolyurethane and polypropylene or the like), a stretchable film or thelike.

In the disposable diaper body 1, the inner surface facing the wearer'sskin is composed of the composite sheet 17 including the non-stretchablenon-woven fabric 171 and the stretchable non-woven fabric 172.

Next, the composite sheet 17 according to the present invention isdescribed. FIGS. 5 and 6 are perspective views of the composite sheet17. The composite sheet 17 is a sheet obtained by joining the expandedstretchable non-woven fabric 172 with the non-stretchable non-wovenfabric 171 at regular intervals, which includes a plurality of gathers174 which is continuously formed in the direction orthogonal to thecontracting direction of the stretchable non-woven fabric 172 in anon-expanded state. Non-stretchable non-woven fabric 171 is bound to thestretchable non-woven fabric 172 at the junction 173. The junction 173is formed in a stretching direction at regular intervals. A non-joinedpart (B in FIGS. 4 and 5), in which the non-stretchable non-woven fabric171 is not bound to the stretchable non-woven fabric 172, constitutesthe plurality of gathers 174 successive in the direction orthogonal tothe stretching direction of the stretchable non-woven fabric 172. Thegathers 174 are formed by a slack portion in the stretch direction ofthe non-stretchable non-woven fabric 171. Meanwhile, the gathers 174 areformed not to overlap each other even when the stretchable non-wovenfabric 172 is not expanded.

The plurality of gathers 174 can be formed to be tilted to the samedirection in the stretching direction as shown in FIG. 5, formed to betilted facing each other in the stretching direction as shown in FIG. 6,or formed to be tilted randomly in the stretching direction of thestretchable non-woven fabric 172, in other words, a mixed configurationof FIGS. 5 and 6. It should be noted that although the gathers 174 shownin FIGS. 5 and 6 have sharp folding lines, the folding lines actuallyare not sharp and are constructed with material of superior feel.

Material for the non-stretchable non-woven fabric 171 can beappropriately selected from, for example, various conventionally-knownnon-stretchable non-woven fabrics, such as spunbonded non-woven fabric,SMS non-woven fabric, point-bonded non-woven fabric, through-airnon-woven fabric, spunlace non-woven fabric, and needlepunched non-wovenfabric, in accordance with the intended purposes of the absorbentarticle. These fabrics may be used alone or in combination. Fiber forthe non-stretchable non-woven fabric 171 can be a sheath-core typecomposite fiber made of polypropylene, polyolefin, polyester, polyamide,polyethylene/polypropylene or polyethylene/polyester, or a side-by-sidecomposite fiber.

The weight of the non-stretchable non-woven fabric 171 can beappropriately selected in accordance with the intended purpose; however,the preferred weight is from 10 to 50 g/m². When the weight is lowerthan 10 g/m², the strength of the non-stretchable non-woven fabric 171can deteriorate. On the other hand, when the weight exceeds 50 g/m²,stiffness can be increased and stretchability can be impaired.

The stretchable non-woven fabric 172 can be produced by a conventionallyknown drawing method such as a gear processing method, and the compositesheet 17 may be constructed with gear-processed stretchable non-wovenfabric 172 and the non-stretchable non-woven fabric 171. Inmanufacturing the composite sheet 17, to make the sheet stretchable, amargin can be made on the non-stretchable non-woven fabric 171, and thenthe stretched stretchable non-woven fabric 172 can be joined thereto.

Material for the gear-processed stretchable non-woven fabric 172 can beappropriately selected from, for example, various conventionally-knownnon-woven fabrics such as spunbond non-woven fabric, melt-blownnon-woven fabric, heat rolled non-woven fabric, SMS non-woven fabricconsisting of spunbond and melt-blown non-woven fabrics, through-airnon-woven fabric, spunlace non-woven fabric and air-laid non-wovenfabric in accordance with the intended purposes of the absorbentarticle. These fabrics may be used alone or in combination. Resinsconstituting these stretchable non-woven fabrics 172 may be, forexample, elastomer resins such as polystyrene, polyurethane and thelike; thermoplastic resins such as polyethylene, polypropylene,polyester, acrylic and the like; and composite fiber such aspolyethylene/polypropylene, polyethylene/polyethylene terephthalat-e andthe like (such as core-in-sheath fiber and side-by-side fiber). Theseresins may be used alone or in combination.

Materials for the entire stretchable non-woven fabric being notgear-processed can be appropriately selected from, for example, variousconventionally-known stretchable non-woven fabrics, such as spunbondednon-woven fabric, point-bonded non-woven fabric, through-air non-wovenfabric, chemically bonded non-woven fabric, melt-blown non-woven fabric,spunlace non-woven fabric, and needlepunched non-woven fabric inaccordance with the intended purposes of the absorbent article. Fiberfor the stretchable non-woven fabric 172 can be elastomer resins such aspolystyrene, polyurethane and the like; thermoplastic resin such aspolyethylene, polypropylene, polyester, acrylic and the like; or sheathcore type or side-by-side composite fiber made of polyolefin, polyester,polyamide, polyethylene/polypropylene or polyethylene/polyester. Inaddition, a stretchable non-woven fabric 172 can be used, obtained bymelt-spinning a urethane-based thermoplastic synthetic resin to obtain aspunbond non-woven fabric, and drawing the spunbond non-woven fabric atleast in one direction to generate elasticity.

The weight of the stretchable non-woven fabric 172 (non-expanded state)can be appropriately selected in accordance with the intended purposes;however, the preferred weight is from 10 to 80 g/m². When the weight islower than 10 g/m², the strength of the stretchable non-woven fabric 172can deteriorate. On the other hand, when the weight exceeds 80 g/m², thepreferred stretching property cannot be obtained due to the increasedstretching stress of the stretchable non-woven fabric 172 and theincreased skew in a case of using a thermoplastic resin.

In addition, the strength of the stretchable non-woven fabric 172(expanded to 200%) is preferably equal to or less than 10 N/50 mm, andmore preferably in the range of 1 to 7 N/50 mm.

The strength of the stretchable non-woven fabric 172 in a 200% expandedstate is measured by the following procedures. It is assumed that thestretching direction of the composite sheet 17 is the longitudinaldirection, and the direction orthogonal to the stretching direction isthe width direction. A test piece is obtained from the non-expandedcomposite sheet 17 of 50 mm in the width direction and 100 mm in thelengthwise direction. Using an autograph-type tensile test machine(AG-1kNI), with a grip spacing of 50 mm (inner size when an upper and alower part of the test piece are held by chucks), and a measuring speedof 500 ram/min, strength at the next site (when the test piece isexpanded to 200% (grip spacing of 100 mm)) is measured.

Even more particularly, after being expanded to 200%, skewness of thestretchable non-woven fabric 172 is preferably no more than 15%, andmore preferably no more than 10%.

The weight of the composite sheet 17 in a non-expanded state ispreferably in the range of 30 to 200 g/m², and more preferably in therange of 65 to 105 g/m². If the weight is less than 30 g/m², thecomposite sheet 17 may be torn due to lack of uniformity and partiallydeteriorated strength. On the other hand, if the weight of the compositesheet 17 exceeds 200 g/m², air permeability is obstructed and ahigh-temperature high-moisture state may result therefrom after wearingfor a long time. The weight of the non-stretchable non-woven fabric 171by itself is preferably in the range of 10 to 50 g/m².

The non-stretchable non-woven fabric 171 is bound to the stretchablenon-woven fabric 172 at the junction 173 at regular intervals. If thegathers 174 of the non-stretchable non-woven fabric 171 is tilted to thesame direction when the stretchable non-woven fabric 172 is not expanded(in the case of FIG. 5), the interval (C in FIGS. 5 and 6) and theheight of a gather 174 preferably satisfy the following Formula 3 whenthe non-stretchable non-woven fabric 171 and the stretchable non-wovenfabric 172 are bound to each other:B<C+2A  Formula 3(in which A is a width of the junction 173 in the stretching directionwhere the non-stretching non-woven fabric 171 is bound to the stretchingnon-woven fabric 172, B is a length in the stretching direction of thearea of the non-stretchable non-woven fabric 171 not bound to thestretchable non-woven fabric 172, and C is a distance between thejunctions 173 in the stretching direction).

By binding the non-stretchable non-woven fabric 171 and the stretchablenon-woven fabric 172 so that Formula 3 is satisfied, a first gather anda second gather, which is adjacent thereto in the stretching direction,of the plurality of gathers 174 can be formed not to overlap each otherin a case where the first and the second gathers lean to the same sidein the stretching direction. In other words, in a case where thecomposite sheet 17 is not expanded, the non-stretchable non-woven fabric171 is stabilized having gathers 174 (or slacks) in the area betweenitself and the neighboring junction 173. In the case in which theneighboring first and the second gathers of the gathers 174 (slacks) areforced to be flattened in the same direction, an apex of the firstgather does not reach the second gather adjacent thereto. In otherwords, apexes of the gathers 174 (slacks) do not exceed the junction 173even when flattened.

This results in a thin composite sheet 17 with low stiffness. Moreover,the composite sheet 17 provides superior comfort and adhesion to awearer's body during wearing, since the gathers 174 do not createfriction against each other. The composite sheet 17 can also preventfriction against the wearer's body.

If the gathers 174 are tilted facing each other (in the case of FIG. 6)when the stretchable non-woven fabric 172 is not expanded (in the caseof FIG. 5), the non-stretchable non-woven fabric 171 and the stretchablenon-woven fabric 172 are preferably bound to each other to satisfy thefollowingB<A+C  Formula 4(in which A is a width of the junction 173 in the stretching directionwhere the non-stretching non-woven fabric 171 is bound to the stretchingnon-woven fabric 172, B is a length in the stretching direction of thearea of the non-stretchable non-woven fabric 171 not bound to thestretchable non-woven fabric 172, and C is a distance between thejunctions 173 in the stretching direction).

By binding the non-stretchable non-woven fabric 171 and the stretchablenon-woven fabric 172 so that Formula 4 is satisfied, a predeterminedgather 174 and another predetermined gather 174 adjacent thereto can beformed not to overlap each other. In other words, in a case where thecomposite sheet 17 is not expanded, the non-stretchable non-woven fabric171 is stabilized having gathers 174 (or slacks) in the area betweenitself and the neighboring junction 173. In the case in which theneighboring first and the second gathers of the gathers 174 (slacks) areforced to be flat facing each other, the apex of the first gather doesnot reach the second gather adjacent thereto. In other words, apexes ofthe gathers 174 (slacks) do not exceed the junction 173 even whenflattened.

This results in a thin composite sheet 17 with low stiffness. Moreover,the composite sheet 17 provides excellent comfort and adhesion to thewearer's body, since the gathers 174 do not create friction against eachother.

It should be noted that an elastic member (not shown) can intervene inthe absorbent article shown in FIGS. 1 to 4 as necessary. The shape ofthe elastic member is not particularly limited and can be appropriatelyselected in accordance with the intended purposes. For example, theelastic member can be strip-shaped, sheet-shaped, plexiform or filiform.The abovementioned elastic members can be used singly or in combinationof two or more types to constitute a disposable diaper body 1.

According to the disposable diaper body 1 of the present embodiment, afirst gather and a second gather adjacent thereto in the stretchingdirection of a plurality of gathers 174 are formed not to overlap eachother, thus resulting in a thin absorbent article with low stiffness.Moreover, the gathers 174 do not create friction against each other.Therefore, a thin, soft absorbent article can be provided, which fitsand adheres comfortably to the wearer's skin.

Additionally, a low apparent thickness and a low repulsive force of thesheet enable easy folding and compact packaging.

Second Embodiment of an Absorbent Article

FIGS. 3 and 4 are top views of a disposable diaper in a flattened stateaccording to a second embodiment of the present invention. The secondembodiment is similar to the first embodiment except that a plurality ofgathers 174 of the composite sheet 17 is arranged selectively in andaround the back body 142.

The present inventors have found through measuring lower-back movementof a wearer with a disposable diaper body 1 on during resting and duringwalking, using a DLT (Direct Linear Transformation) method that adhesionof the disposable diaper body 1 to the wearer's body is the worst at thevicinity of the buttocks. In other words, the inventors have found thatif adhesion in the vicinity of the buttocks can be improved, the comfortof the whole disposable diaper body 1 can be improved. Thus, as shown inFIG. 3, the composite sheet 17 can be arranged in the vicinity of theback body 142 of the disposable diaper body 1, namely on the skincontacting side of the area contacting the wearer's buttocks (back body)during wearing.

Alternatively, having determined areas of the worst adhesion to thewearer's body by the DLT method, the composite sheet 17 can be arrangedonly in the specified areas in the area contacting the wearer's buttocks(as shown in FIG. 4). In this case, the composite sheet is arranged at apredetermined distance away, in the width direction WD, from acenterline CL equally dividing the back body, and at each of a pair ofareas that are symmetrical to the centerline CL.

According to the disposable diaper body 1 of the present embodiment, inaddition to the effect of the first embodiment, by arranging thecomposite sheet 17 at the areas of the worst adhesion to the wearer'sbody, in the area contacting the wearer's buttocks, an absorbent articleof superior comfort can be provided. In addition, an absorbent articleof superior ability to follow can also be provided.

Composite Sheet

The composite sheet 17 stated above can be used as a composite sheet foran inner covering of the absorbent article, in addition to the use forthe disposable diaper body 1. Such a composite sheet is thin, superiorin flexibility and in feel, has superior cushioning property, and thuscan be used for sanitary products in addition to disposable diapers.

Manufacturing Method for Composite Sheet.

The composite sheet 17 is obtained, as stated above, by laminating(binding) a non-stretchable non-woven fabric 171 and a stretchablenon-woven fabric 172. Firstly, a stretchable non-woven fabric 172 isproduced by gear processing.

FIG. 7 is a diagram showing a method of manufacturing a stretchablenon-woven fabric 172 by gear processing. A stretchable non-woven fabricis manufactured by compressing a high-density sheet 3 by a gear edger 2such as a pair of embossing rolls shown in FIG. 7, thus stretching thesheet 3 to obtain low-density areas 1722. The gear edger 2 has a cogarea 21 in which a plurality of cogs is arranged. A pair of the gearedgers 2 rotates facing each other with the sheet 3 therebetween andengages each other, thus compressing and reducing the thickness of thesheet 3 by the pressure at the apex of the cog area 21. By rotating apair of gear edgers 2 tucking the sheet 3, the sheet 3 is compressed bythe cog area 21, and high-density regions 1721 and low-density regions1722 are obtained alternately at the interval of the cogs.

The method shown in FIG. 7 includes a mating plate, embossing,thermoforming, high-pressure hydraulic molding and injection molding. Inaddition to the manufacturing method shown in FIG. 7, in the case usinga low-density non-woven fabric, for example, the non-woven fabric can beonce melted and formed into a film by heat or ultrasonic processing toadd high-density regions 1721. In this case, a heat-treated regionbecomes a high-density region 1721, and an untreated region becomes alow-density region 1722. Even more particularly, for example, thehigh-density regions 1721 may be formed by collective embossed lines ordots. In addition to a gear-processed stretchable non-woven fabric 172,a stretchable non-woven fabric 172 obtained by drawing a non-drawnnon-woven sheet can be used.

In particular, for example, by drawing a non-woven fabric produced by aspunbond method in a machine direction MD, an appropriate stretchabilityin width and lengthwise directions can be obtained. Additionally, bycombining a non-stretchable non-woven fabric 171, a strength requiredfor an absorbent article can be obtained. In FIG. 7, MD is a directionparallel to a machine direction of a fiber web at the production of thestretchable non-woven fabric 172. CD is a direction orthogonal to themachine direction of the fiber web, namely MD.

A heating method, drawing temperature, and drawing ratio of the drawingprocessing of a non-drawn non-woven sheet can be appropriately set inaccordance with the intended purposes of composite sheet 17.

The stretchable non-woven fabric 172 obtained by the drawing processingis expanded and bound to a non-stretchable non-woven fabric 171 via ajunction 173 (for example, see FIG. 5). Even more particularly, thestretchable non-woven fabric 172 is bound to the non-stretchablenon-woven fabric 171 being expanded preferably at least to 150%, andmore preferably to approximately 200%. If the stretchable non-wovenfabric 172 is bound in a state being expanded to less than 150%, astretchability required for a composite sheet 17 may not be fullyobtained.

The binding method is not particularly limited, but each non-wovenfabric preferably adheres only at the junction 173 by hot-melt adhesionusing an elastomer-based resin as a major component. Since the coatingpattern of hot-melt adhesion is arranged intermittently in thestretching direction on a non-bound portion of the non-stretchablenon-woven fabric 171 (B of FIG. 4 or 5) in a direction orthogonal to thestretching direction, successive gathers 174 are easily developed whenthe stretchable non-woven fabric 172 contracts. The coating patterns ofhot-melt adhesion include pattern coating or solid pattern coating suchas spiral coating, controlled seam coating, coater coating, curtaincoater coating, summit-gun coating, curtain spray coating, omegacoating, whole coating, multi-dot coating, etc., for example. The weightof an adhesive for hot-melt adhesion is preferably in the range of 1 to5 g/m². It should be noted that it is obvious that the non-stretchablenon-woven fabric 171 adheres only to the junction 173 so that theFormula 3 or 4 is satisfied. Once the non-stretchable non-woven fabric171 and the stretchable non-woven fabric 172 are bound and thestretchable non-woven fabric 172 contracts, a plurality of gathers 174is compressed by an edger or a belt to tilt to the same side as shown inFIG. 4, or to tilt facing each other as shown in FIG. 5.

EXAMPLES

Examples of the present invention are described hereafter. However,these examples are illustrative only and the present invention shouldnot be construed as being limited to these examples.

Areas of the worst adhesion to a wearer's body were determined in adisposable diaper 1 by the DLT method. A disposable diaper body 1 wasprepared with composite sheets 17 arranged in the areas of the worstadhesion, the vicinity of the buttocks, as shown in FIG. 4 (hereinafterreferred to as Example 1). Then, subjective evaluation was undertaken by12 female panel members in their late fifties to seventies to assess fitand adhesion to the wearer's skin and comfort during wearing thereof.The comfort during wearing was assessed by comfortable fit of thedisposable diaper body 1 and pleasant texture of an absorbent body 13.

The subjective evaluation included steps of: wearing a marketeddisposable diaper, assessing the comfort immediately after putting on,assessing the comfort with various postures such as sitting on a chair,sitting with legs folded under the body and squatting, and assessing thecomfort after three minutes of walking. The marketed disposable diaperwas used as a standard sample and hereinafter is referred to as StandardExample.

The subjective evaluation also included steps of: wearing Example 1 andassessing the comfort during wearing in the same way as with StandardExample. Assessment was made based on an eleven point scale from −5 (theworst) to +5 (the best), relative to a comfort of Standard Example as 0.

The subjective evaluation also included steps of: wearing two othermarketed disposable diapers (hereinafter referred to as ComparativeExamples 1 and 2) and assessing the comfort during wearing in the sameway as with Example 1. The results are shown in FIGS. 8 and 9.

According to FIGS. 8 and 9, it was determined that Example 1 was of thebest comfort to a wearer's body. It was also determined that theabsorbent body 13 had the most pleasant texture. As a result of theseassessments, Example 1 was found to be a disposable diaper of bettercomfort during wearing and of better adhesion than conventionallymarketed disposable diapers.

What is claimed is:
 1. A composite sheet comprising: a stretchablenon-woven fabric which expands and contracts in at least one direction,the stretchable non-woven fabric comprising high-density regions andlow-density regions arranged alternatively with each other in astretching direction to allow expansion and contraction of thestretchable non-woven fabric; a non-stretchable non-woven fabric; ajunction which binds intermittently the stretchable non-woven fabric tothe non-stretchable non-woven fabric in the stretching direction; and aplurality of gathers which is formed by loosening a non-bound area ofthe non-stretchable non-woven fabric in a contracted state, and isarranged along a direction intersecting the stretching direction,wherein an apex of each gather does not reach the neighboring gatherwhen the gathers lean to one side of the stretchable direction, and thehigh-density regions and the low-density regions are formed throughoutthe stretchable non-woven fabric including portions not includingjunctions.
 2. The composite sheet of claim 1, wherein a weight basis ofthe stretchable non-woven fabric is greater than a weight basis of thenon-stretchable non-woven fabric.
 3. The composite sheet of claim 1,wherein the non-stretchable non-woven fabric has a basis weight of 10 to50 g/m².
 4. The composite sheet of claim 1, wherein the stretchablenon-woven fabric has a basis weight of 10 to 80 g/m².
 5. The compositesheet of claim 1, wherein the stretchable non-woven fabric has astrength in a 200% expanded state of 1 to 7 N/50 mm.
 6. The compositesheet of claim 1, wherein the composite sheet has a weight basis of 30to 200 g/m².
 7. The composite sheet of claim 1, wherein the compositesheet has a weight basis of 65 to 105 g/m².
 8. The composite sheet ofclaim 1, wherein the plurality of gathers are all tilted in onedirection.
 9. The composite sheet of claim 1, wherein the plurality ofgathers are tilted alternating directions to face one another.
 10. Thecomposite sheet of claim 1, wherein the plurality of gathers are tiltedrandomly.
 11. The composite sheet of claim 1, wherein the junctioncomprises a hot-melt adhesive.
 12. The composite sheet of claim 11,wherein the hot melt adhesive comprises an elastomer-based resin. 13.The composite sheet of claim 11, wherein the weight basis of the hotmelt adhesive is in the range of 1 to 5 g/m².
 14. The composite sheet ofclaim 1, wherein the composite sheet satisfies the following formula inwhich A is a width in the stretching direction of the junction where thenon-stretching non-woven fabric is bound to the stretching non-wovenfabric, B is a length in the stretching direction of a region of thenon-stretchable non-woven fabric not bound to the stretchable non-wovenfabric, and C is a distance in the stretching direction between each ofthe junctions: B<C+2A.
 15. The composite sheet of claim 1, wherein thecomposite sheet satisfies the following formula in which A is a width inthe stretching direction of the junction where the non-stretchingnon-woven fabric is bound to the stretching non-woven fabric, B is alength in the stretching direction of a region of the non-stretchablenon-woven fabric not bound to the stretchable non-woven fabric, and C isa distance in the stretching direction between each of the junctions:B<A+C.